Thanks all. I just got done letting it run through a full cycle. I started with 6 gallons of strike water at room temp and 15 gallons in the HLT / HEX (Heat Exchanger). Ramped up to 114 by pressing "Preheat" and was prompted to dough-in. The app has a configurable dough-in compensation for room-temp grain... my config was set to 10 degrees, so if I was really brewing I would have expected it to level out at around 104.

At this point I pressed "Start" and pretty much walked away.

For this test run, I ran all six configurable stages... a twenty minute Acid Rest was done at 104 degrees; ramped to 126 degrees and did a twenty minute Protein Rest; ramped to 140 degrees for a twenty minute Intermediate Rest; ramped to 153 for a sixty minute Saccharification Rest; ramped to 170 for the mash-out and sounded the alarm. While mashing out, the HEX ramped to 178 for the Sparge and held it until the mash out was complete.

I gotta say, it was a good feeling to see it all go well - a LOT of effort has gone into getting it to this point.

A few questions besides all the later details you must answer that will come up in the future from many of us.

With 15 gallons in the HLT plus 6 gallons strike water both at room temp (not counting the grain temp loss) how long did it take to heat the total 21 gallons volume with your 5.5 KW 220 volt element in the HLT? (HLT 15 gallons plus 6 gallons of strike water) from room temp to 104*F in minutes?
Again same question in minutes from 104*F to 126*F, 126*F to 153*F, 153*F to 170*F then to 178*F during mash out?

This evenings test run didn't include statistics - there is a bug that I haven't had a chance to look into. I will definitely be running several more test runs this next week and report back. I can say for certainty that the 5500w element is noticably faster heating than my old 3500w element.

Right now, the stats would be semi-flawed as I am still tweaking the algorithm that keeps the HEX temp in check with the set point for the mash. I had a HEX differential of 3 degrees in the config - meaning that the HEX would only go 3 degrees above the temp it was currently ramping the mash to. I am certain it would have raised the mash's temp faster if I had a higher HEX differential, but the trade-off is potentially overshooting the target temp or potentially scorching the wort...